EVENT-TRIGGERED SLIDING MODE CONTROL FOR CONSTRAINED NETWORKED CONTROL SYSTEMS

The paper describes a Non-linear Control (ETNC) approach for constrained Networked Feedback Control Systems (NFCS). The real-time controller execution is implemented based on the Event-triggering paradigm. A  nonlinear variable structure is used for the controller design. The nonlinear approach is based on the predefined sliding variable defined by the system states with a nonlinear switching function. The system's stability is analyzed regarding the evolution of the sliding variable. The Event-Triggered operation of the nonlinear controller is based on the prescribed triggering rule. The stability boundary of the sliding variable is subject to the preselected triggering condition, whose selection is a tradeoff of system performance, networks constraints and transmission capabilities. The main focus of the Event triggering approach is lowering network resources utilization in the steady-state behavior of the NFCS. The presented approach ensures a non-zero inter-event time of controller execution, which enables scheduling and optimization of the network operation regarding the network constraints and real-time system performance. The efficiency of the presented method is presented with a comparison of the classical time triggering approach.  The real measurement supports the results

Quasipolynomial Approach to Simultaneous Robust Control of Time-Delay Systems

A control law for retarded time-delay systems is considered, concerning infinite closed-loop spectrum assignment. An algebraic method for spectrum assignment is presented with a unique optimization algorithm for minimization of spectral abscissa and effective shaping of the chains of infinitely many closed-loop poles. Uncertainty of plant delays of a certain structure is considered in a sense of a robust simultaneous stabilization. Robust performance is achieved using mixed sensitivity design, which is incorporated into the addressed control law

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This paper presents the synthesis of an optimal robust controller with the use of pole placement technique. The presented method includes solving a polynomial equation on the basis of the chosen fixed characteristic polynomial and introduced parametric solutions with a known parametric structure of the controller. Robustness criteria in an unstructured uncertainty description with metrics of norm ℋ∞ are for a more reliable and effective formulation of objective functions for optimization presented in the form of a spectral polynomial with positivity conditions. The method enables robust low-order controller design by using plant simplification with partial-fraction decomposition, where the simplification remainder is added to the performance weight. The controller structure is assembled of well-known parts such as disturbance rejection, and reference tracking. The approach also allows the possibility of multiobjective optimization of robust criteria, application of mixed sensitivity problem, and other closed-loop limitation criteria, where the common criteria function can be composed from different unrelated criteria. Optimization and controller design are performed with iterative evolution algorithm

Event-triggered second-order sliding mode controller design and implementation

The paper presents an event-triggered higher-order sliding mode controller design. The event-triggering technique is the alternative approach to real-time controller execution, unlike the classic time-triggering technique, which is not time-dependable and is governed by the triggering policy. The technique is suitable for system resource relaxation in case of computation burden or network usage mitigation. The paper describes the stability analysis of the super-twisted sliding mode controller based on input-to-state stability notation. The stability analysis introduces a triggering policy related directly to the ultimate boundness of the system states and preselected sliding variables. The controller time execution with the selected triggering condition prevents the exhibition of the Zeno phenomena, where the minimal inter-event time of the controller has a positive non-zero lower bound. The minimal value of the inter-event time is related directly to the controller parameters and triggering bound, the selection of which is given with the derived stability conditions regarding the designer’s objective. Preventing the fast nonlinear controller execution, especially close to the sliding manifold, also alleviates the chattering phenomena effectively, which is a primal drawback, and limits the usage of the controller on various systems. The method’s efficiency is verified with the hardware-in-the-loop system, where the dynamic and robustness of the triggering approach are compared to the standard time-triggered execution technique.Članek predstavlja sintezo dogodkovno praženega regulatorja višjega reda po metodi drsne spremenljivke. Dogodkovno proženje je alternativni pristop, h klasičnemu časovno praženemu izvajanja regulatorja, kjer z razliko klasičnega pristopa ni časovno odvisen in se izvaja glede na predpisan dogodek. Dogodkovno proženje je primerno za sisteme, kjer je pomembno varčevanje z energijo, mrežno vodenje, upravljanje dogodkov z nižjo frekvenco izvajanja in optimizacijo virov z nižjo kompleksnostjo izvajanja nalog. Delo opisuje analizo stabilnosti notranjih stanj \u27Super-Twisted\u27 nadzornega algoritma v dogodkovnem načinu. Analiza vpeljuje dogodkovno pravilo proženja, ki zagotavlja strogo omejenost drsne spremenljivke in notranjih stanj. Prav tako se analiza posveča Zeno fenomenu, ki ga je moč odpraviti s pravilno izbiro prožilnega dogodka. Odprava Zeno-fenomena je dokazana s strogo pozitivnim minimalnim časom izvajanja med dvema zaporednima dogodkoma, kjer je čas izvajanja odvisen od izbire parametrov regulatorja. Prav tako je dokazano, da je v dogodkovnem proženju odpravljeno hitro preklapljanje in brstenje izhoda regulatorja blizu ničelne vrednosti drsne spremenljivke v n-dimenzionalnem prostoru. Metoda je preizkušena na realnem sistemu in je verificirana glede na klasično časovno izvedbo regulacijskega algoritma

Robust pole placement technique with optimization of norm Hinf

V disertaciji je predstavljena nova metoda sinteze robustnega regulatorja s tehniko pomikanja polov. Metoda vključuje rešitev polinomske enačbe na osnovi izbranega karakterističnega polinoma, s pomočjo Manabe-jeve standardne oblike polinoma ter vpeljanimi parametričnimi rešitvami. Parametrične rešitve so vpeljane direktno v strukturo regulatorja. Na osnovi izbranih parametričnih rešitev se s pomočjo modelov odstopanj in vrednotenjem norme ‖∙‖_∞ oceni robustnost zaprto zančnega sistema. Postopek načrtovanja z optimizacijo je izvedena z genetskim algoritmom Diferencialna evolucija – DE. Optimizacijski algoritem DE tekom optimizacije določa sub-optimalno rešitev na osnovi koeficientov spektralnega kvadratičnega polinoma in Šiljakovim absolutnim testom stabilnosti. Stabilnost sintetiziranega regulatorja je možno, ob postavljeni zahtevi stabilnosti regulatorja tekom optimizacije testirati s Lipatov-im kriterijem. Oba uporabljena pristopaŠiljakov test in Liaptov kriterij, preverjata lastnost robustne stabilnosti in stabilnost regulatorja na osnovi koeficientov danega polinoma. Kriterija sta primerna, za avtomatizirano načrtovanje zaprto zančnega sistema in uporabo v sklopu optimizacijskih algoritmov, kot je DE. Primer načrtovanja regulatorja z razvito metodo, je predstavljen za izbran problem servo sistema z enosmernim elektromotorjem. Tekom postopka sinteze upoštevamo odstopanje parametrov motorja ter spremembo delovne točke zaradi spremenljivega bremena.The dissertation describes the area of robust controller synthesis with pole placement technique. The new method includes solving a polynomial equation on the basis of the chosen characteristic polynomial using the Manabe standard polynomial form and parametric solutions. Parametric solutions are introduced directly into the structure of the controller. On the basis of the chosen parametric solutions the robustness of a closed-loop system is assessed through uncertainty models and assessment of the norm ‖∙‖_∞. The design procedure and the optimisation are performed with a genetic algorithm Differential evolution – DE. The DE optimisation method is determining a suboptimal solution throughout the optimisation on the basis of a spectrally square polynomial and Šiljak\u27s absolute stability test. In case that stabile controller is demanded, the stability of the designed controller can be checked during the optimisation with Lipatov\u27s stability test. Approaches like Šiljak’s test and Lipatov’s test, checks the robustness criterion and controller stability characteristics on the basis of polynomial’s coefficients. Both are very convenient for automated design of the closed-loop controlled systems and for application that include optimisation algorithms such as DE. In the dissertation an example of the robust controller synthesis with a presented method is described for the control of a servo mechanism with BDC electric motors, where uncertainty of the motor parameters and changing load is considered

Optimal robust motion controller design using multi-objective genetic algorithm

This paper describes the use of a multi-objective genetic algorithm for robust motion controller design. Motion controller structure is based on a disturbance observer in an RIC framework. The RIC approach is presented in the form with internal and external feedback loops, in which an internal disturbance rejection controller and an external performance controller must be synthesised. This paper involves novel objectives for robustness and performance assessments for such an approach. Objective functions for the robustness property of RIC are based on simple even polynomials with non-negativity conditions. Regional pole placement method is presented with the aims of controllers% structures simplification and their additional arbitrary selection. Regional pole placement involves arbitrary selection of central polynomials for both loops, with additional admissible region of the optimized pole location. Polynomial deviation between selected and optimized polynomials is measured with derived performance objective functions. A multi-objective function is composed of different unrelated criteria such as, robust stability, controllers\u27 stability and time performance indexes of closed loops. The design of controllers and multi-objective optimization procedure involve a set of the objectives, which are optimized simultaneously with a genetic algorithm - Differential evolution

Razvoj izdelka s pomočjo večkriterijske analize

The trend regarding the development of sanitary fittings is forecasted by the use of a developed model of multi-criteria analysis. In this analysis a multi-dimensional space is used, which enables the establishment of a time argument in comparison to product parameters. The establishment of product parameters is achieved by means of internal company information and market needs. In this way it is possible to establish an innovative environment for the development of new products. This paper indicates various ways of dealing with product development, on the basis of which the method of multi-criteria analysis for establishing future trends in product development is acquired.The trend regarding the development of sanitary fittings is forecasted by the use of a developed model of multi-criteria analysis. In this analysis a multi-dimensional space is used, which enables the establishment of a time argument in comparison to product parameters. The establishment of product parameters is achieved by means of internal company information and market needs. In this way it is possible to establish an innovative environment for the development of new products. This paper indicates various ways of dealing with product development, on the basis of which the method of multi-criteria analysis for establishing future trends in product development is acquired